两种早期人类的骨骼对比Comparing two early human skeletal systems

Variations in the skeletal systems of two early types of human are illustrated in this diagram. Overall, we can see that australopithecus afarensis had a heavier body and much longer arms, while homo erectus was slimmer and had more developed joints. To begin with the upper half of the body, australopithecus afarensis had a much broader chest and waist than homo erectus, giving it a rounder appearance. The former had much longer arms and larger hands, which would have been useful for climbing trees. As for the lower half of the body, we can see that homo erectus had proportionately longer legs and larger hip, knee and ankle joints. The feet of homo erectus were also smaller and more arched, with shorter toes. These differences meant that homo erectus was better suited to long-distance running. In conclusion, we can see significant changes in the development of early humans from the diagram. Homo erectus is more similar to contemporary human beings with its long legs and arched feet. The physical differences are clearly related to differences in the lifestyles of tree climbers and endurance runners.